Interactions between Phospholipids and Polymers with Time Resolved Fluorescence Spectroscopy

Interactions between macromolecule species and fluorescently labeled phospholipids were explored in supported lipid bilayers (SLBs). The concentration and the lateral mobility of the labeled phospholipids within the confocal volume were determined via fluorescence correlation spectroscopy. Low molecular weight polystyrene was used for the neutral charged macromolecule. Three separate concentrations of polystyrene were used and a significant change in lateral mobility of phospholipids was found for the SLB doped with all three concentration of styrene from polystyrene (molecular weight = 1000). Polyester with mimic lysine pendant groups was used for the cationic polymer at physiological pH. A large decrease in the mobility of head labeled lipids was found when the polyester was introduced to the bilayer. The same polyester was used on an experiment with SLBs doped with negatively charged, tail labeled phospholipids. However, a faster diffusion coefficient was found for the SLB when introduced to the polycationic molecule. This is contradicting to previous reports but this is just a preliminary observation. More experiments need to be completed to further determine these relationships. Overall, important groundwork has been completed to help describe the dynamics of the lipid-macromolecule interface